A new screening test for colorectal cancer is evaluated in 1,000 individuals: 100 have cancer (by gold standard). The test correctly identifies 85 cases and misses 15. Of 900 without cancer, the test is negative in 720 and positive in 180. The specificity of this test is:

• A 85%
• B 72%
• C 82.5%
• D 80% ✓

Explanation

Specificity = True Negatives / (True Negatives + False Positives) = 720 / (720 + 180) = 720 / 900 = 80%. Sensitivity = 85/100 = 85%. The 180 false positives reduce specificity; in colorectal cancer mass screening this produces a substantial burden of follow-up colonoscopies for individuals without cancer.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.